For a MOC incorporating all flagships of Lego Space (not including Star Wars), I'm trying to figure out which Lego Space spaceships can actually be considered "flagships". Of course, I have an idea of my own, but I am certainly biased, so I'd like to put the question to my fellow CSFers:

Which five Lego Space spaceships must be included in a definite list of flagships of Lego Space?

Sets from Star Wars are not eligible. Other than that, any theme is allowed.